Passive pump

ABSTRACT

A method for repairing a heart includes identifying a heart of a patient as having a reduced ejection fraction. In response to the identifying, wall stress of a ventricle of the heart is reduced by implanting apparatus that facilitates cyclical moving of fluid that is not blood of the patient into and out of the ventricle of the heart. During ventricular diastole, a volume of the fluid is moved into the ventricle in a manner that produces a corresponding decrease in a total volume of blood that fills the ventricle during diastole. During ventricular systole, the volume of the fluid is moved out of the ventricle in a manner that produces a corresponding decrease in a total volume of the ventricle during isovolumetric contraction of the ventricle. Other embodiments are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part application of:

U.S. patent application Ser. No. 16/879,164 to Gross, filed May 20,2020, entitled, “Passive pump,” and

PCT Patent Application PCT/IL2021/050567 to Gross, filed May 18, 2021,entitled, “Passive pump,” which claims the priority from and is acontinuation application of U.S. patent application Ser. No. 16/879,164to Gross, filed May 20, 2020, entitled, “Passive pump.”

Each of these applications is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates in general to heart repair. Morespecifically, the present invention relates to a method of repairing afailing heart utilizing a passive device which assists a ventricle ofthe heart.

BACKGROUND OF THE INVENTION

Heart failure is a condition in which the heart cannot pump enough bloodto meet the body's needs. In some cases, the heart cannot fill withenough blood. In other cases, the heart cannot pump blood to the rest ofthe body with enough force.

Heart failure develops over time as the heart's pumping action growsweaker. The condition can affect one or both sides of the heart.

Systolic heart failure occurs when the contraction of the muscle wall ofthe left ventricle malfunctions, which compromises its pumping action.This causes a decrease in the ejection fraction below the normal range,and gradually, left ventricular remodeling occurs in the cardiac tissuewhich causes enlargement of the ventricle. The remodeling manifests asgradual increases in left ventricular end-diastolic and end-systolicvolumes, wall thinning, and a change in chamber geometry to a morespherical, less elongated shape. This process is usually associated witha continuous decline in ejection fraction. In general, left-sided heartfailure leaves the heart unable to pump enough blood into thecirculation to meet the body's demands, and increasing pressure withinthe heart causes blood to back up in the pulmonary circulation,producing congestion.

SUMMARY OF THE INVENTION

In some applications of the present invention, apparatus is providedthat is implantable at a heart of a patient and facilitates cyclicalmoving of fluid that is not blood of the patient into and out of aventricle of the heart. That is, during ventricular diastole, a volumeof the fluid is moved into the ventricle in a manner that produces acorresponding decrease in a total volume of blood that fills theventricle during diastole. During ventricular systole, the volume of thefluid is moved out of the heart in a manner that produces acorresponding decrease in a total volume of the ventricle duringisovolumetric contraction of the ventricle. In such a manner, thepressure rise in the ventricle occurs at a lower volume than thepressure rise would otherwise occur in a heart of a healthy subject.Typically, the fluid in the passive pump is moved between components ofthe passive pump responsively to pressure increases and decreasesassociated with stages of the cardiac cycle. Therefore, the pump isconsidered passive. The passive pump is typically not operably connectedto machinery or circuitry which helps facilitate movement of the fluidbetween the components of the pump.

The apparatus typically comprises (a) a bag that is noncompliant, (b) acompliant balloon, (c) a conduit disposed between and in fluidcommunication with the bag and the compliant balloon, and (d) a volumeof fluid disposed within an inner space defined by the apparatus. Thevolume of fluid is passable between the bag and the compliant balloonvia the conduit passively and responsively to changes in pressureassociated with respective stages of the cardiac cycle.

Except where indicated to the contrary, applications of the presentinvention described as utilizing a “fluid” may be implemented usingeither a liquid or a gas.

For some applications of the present invention, the apparatus comprisesa second bag that is noncompliant, instead of the compliant balloon. Inthis case, a spring is typically, but not necessarily, coupled to thesecond bag to facilitate ejecting of the fluid from within the secondbag.

Typically, the bag is positionable within the ventricle (e.g., the leftventricle or the right ventricle), and the compliant balloon, or secondbag, is positionable outside the ventricle (e.g., in the right atrium,in the superior vena cava, in the inferior vena cava, or any suitableplace outside of the heart).

For some applications, the bag is positionable within the ventricle, thecompliant balloon is positionable outside of the heart, and the conduitis disposed transmyocardially. The compliant balloon is configured toexpand upon transfer of the fluid into the balloon from the bag, and tocontract upon passage of at least part of the fluid out of the balloon.During ventricular diastole, the balloon contracts and expels the fluid,through the conduit, into the bag within the ventricle. Duringventricular systole, while the aortic valve of the heart is closed, theleft ventricle contracts, causing a volume of the fluid to be expelledfrom the bag, through the conduit, and into the balloon, in a mannerthat produces a corresponding decrease in a total volume of theventricle during isovolumetric contraction of the ventricle. It isadvantageous to reduce the volume of the ventricle during isovolumetriccontraction of the ventricle in order to facilitate reverse remodelingof the ventricle, such that the heart returns to a healthy geometry.Typically, this is accomplished since this application of the inventionreduces the extent to which the ventricular wall is stretched at highpressure. This yields acute and chronic reduction in ventricular wallstress, which the inventor hypothesizes will result (typically over thecourse of months) in the desired reverse remodeling describedhereinabove.

For some applications, the bag is positionable within the left ventricleof the patient while the compliant balloon or second bag is positionableoutside of the left ventricle. For example, the compliant balloon orsecond bag may be positionable in the right atrium, the inferior venacava, or the superior vena cava.

For some applications of the present invention, the passive pumpcomprises first and second noncompliant bags. A spring is coupled to oneof the bags that is designated for positioning outside of the ventricle.The spring absorbs energy during filling of the bag, e.g., typicallyduring ventricular systole, and releases the energy in order to expelthe fluid from within the bag, e.g., during ventricular diastole, andinto the other bag that is disposed within the ventricle.

There is therefore provided, in accordance with an application of thepresent invention apparatus, including:

a flexible intraventricular receptacle configured to be positionedwithin a ventricle of a heart of a patient, the flexibleintraventricular receptacle being configured to assume a first volumeupon passage of fluid that is not blood into the flexibleintraventricular receptacle and a second volume upon passage of at leastpart of the fluid out of the flexible intraventricular receptacle, thesecond volume being smaller than the first volume;

an expandable extraventricular receptacle configured to be positionedoutside of the ventricle, the expandable extraventricular receptaclebeing configured to expand upon transfer of the fluid into theexpandable extraventricular receptacle from the intraventricularreceptacle and to contract upon passage of at least part of the fluidout of the expandable extraventricular receptacle; and

a conduit disposed between and in fluid communication with the flexibleintraventricular receptacle and the expandable extraventricularreceptacle, the conduit being configured to allow passage of the fluidbetween the intraventricular and the extraventricular receptacles,

the apparatus is configured such that when the intraventricularreceptacle is disposed within the ventricle, the extraventricularreceptacle is disposed outside of the ventricle, the apparatus isconfigured to facilitate the passage of the fluid between theintraventricular and the extraventricular receptacles responsively to acardiac cycle of the heart, in a manner in which:

-   -   during ventricular diastole, the extraventricular receptacle        contracts and expels the fluid, through the conduit, into the        intraventricular receptacle, and    -   during ventricular systole, while an aortic valve of the heart        is closed, a volume of the fluid is expelled from the        intraventricular receptacle, through the conduit, into the        extraventricular receptacle, in a manner that produces a        corresponding decrease in a total volume of the ventricle during        isovolumetric contraction of the ventricle, and

the apparatus further includes an energy-storage element coupled to theexpandable extraventricular receptacle and configured to:

-   -   absorb energy upon filling of the expandable extraventricular        receptacle from a first state to a second, expanded state, and    -   release the energy to return the expandable extraventricular        receptacle from the second, expanded state to the first state.

In an application, the extraventricular receptacle is configured to bepositioned at an extracardiac location, and the conduit defines atransmyocardial conduit configured to be disposed passing through a wallof the heart.

In an application, the extraventricular receptacle includes a bellows,and the energy-storage element is coupled to the bellows in a manner inwhich the bellows is disposed between the intraventricular receptacleand the energy-storage element.

In an application, the energy-storage element is configured to:

assume a compressed, longitudinally-shortened state upon the filling ofthe bellows from the first state to the second, expanded state, and

return the bellows from the second, expanded state to the first state.

In an application, the energy-storage element includes a coil spring.

In an application, the energy-storage element includes a shape-memorymaterial.

In an application, the apparatus includes a scaffolding surrounding thebellows and the energy-storing element, and the energy-storage elementis coupled at a first end of the energy-storage element to an outersurface of the bellows, and at a second end of the energy-storageelement to a portion of the scaffolding, during absorbing and releasingof the energy by the energy-storage element, the first end of theenergy-storage element moves, respectively, toward and away from thesecond end of the energy-storage element.

In an application, the extraventricular receptacle includes a bellows,and the energy-storage element is coupled to the bellows by surroundingthe bellows at least in part.

In an application, the energy-storage element includes a coil springthat at least partially surrounds the bellows and is configured to:

assume a longitudinally-elongated state upon the filling of the bellowsfrom the first state to the second, expanded state, and

return the bellows from the second, expanded state to the first state.

In an application, the coil spring wraps around the bellows betweenfolds of the bellows.

In an application, the energy-storage element includes a plurality ofstruts surrounding the extraventricular receptacle, a respective portionof each of the struts is configured to:

assume a longitudinally-elongated state upon the filling of theexpandable extraventricular receptacle from the first state to thesecond, expanded state,

assume a longitudinally-shortened state, and

return the expandable extraventricular receptacle from the second,expanded state to the first state during a transition of theenergy-storage element from the longitudinally-elongated state towardthe longitudinally-shortened state.

In an application, in the longitudinally-shortened state, the respectiveportion of each of the struts is shaped so as to define a bend whichprojects laterally away from a central longitudinal axis of theapparatus.

In an application, each strut extends longitudinally along an externalsurface of the extraventricular receptable in a direction (1) from aportion of the extraventricular receptable that is furthest from theintraventricular receptable, and toward (2) the intraventricularreceptable.

In an application, the apparatus includes a stent structure, and a firstportion of the stent structure surrounds the conduit, and theenergy-storage element defines a second portion of the stent structurethat surround the extraventricular receptacle.

In an application:

a part of the first portion of the stent structure surrounds a portionof the intraventricular receptacle,

the stent structure is (i) compressed during delivery of the apparatusinto a body of a patient, and (ii) expandable during implantation of theapparatus in the body of the patient, and

once expanded, the first portion of the stent structure is shaped so asto define (1) a narrowed portion at the conduit and (2) a wider portionthan the narrowed portion, at the part of the first portion of the stentstructure that surrounds the portion of the intraventricular receptacle.

In an application, the energy-storage element includes a mesh having afirst portion surrounding the extraventricular receptacle, the firstportion of the mesh is configured to:

absorb the energy upon the filling of the expandable extraventricularreceptacle from the first state to the second, expanded state, and

release the energy to return the expandable extraventricular receptaclefrom the second, expanded state to the first state.

In an application, the apparatus is configured such that as the firstportion of the mesh releases the energy, the first portion of the meshtransitions toward a longitudinally-shortened state in which the firstportion of the mesh expands radially and shortens longitudinally, withrespect to a central longitudinal axis of the apparatus.

In an application, a second portion of the mesh surrounds the conduit,and a third portion of the mesh surrounds a portion of theintraventricular receptacle.

In an application:

the mesh is (i) compressed during delivery of the apparatus into a bodyof a patient, and (ii) expandable during implantation of the apparatusin the body of the patient, and

once expanded, the second portion of the mesh is shaped so as to definea narrowed portion at the conduit and the third portion of the mesh isshaped so as to define a wider portion than the narrowed portion, at theportion of the intraventricular receptacle.

In an application, the apparatus further includes the fluid, and thefluid has a volume of 10-80 ml which is passable between the flexibleintraventricular receptacle and the expandable extraventricularreceptacle via the conduit.

In an application, the intraventricular receptacle is anintra-left-ventricular receptacle.

In an application, the apparatus further includes a stent structure, andthe stent structure surrounds the conduit.

In an application, the apparatus further includes a scaffolding disposedwithin the intraventricular receptacle, the scaffolding being configuredto prevent dislodging of the intraventricular receptacle from within theventricle.

In an application, the apparatus further includes a rod disposed withinthe intraventricular receptacle, the rod being configured to preventdislodging of the intraventricular receptacle from within the ventricle.

In an application, the expandable extraventricular receptacle iscompliant.

In an application, wall compliance of the expandable extraventricularreceptacle is at least three times wall compliance of the flexibleintraventricular receptacle.

In an application, the expandable extraventricular receptacle and theflexible intraventricular receptacle are configured such that, in theabsence of any external forces applied to the expandableextraventricular receptacle and the flexible intraventricularreceptacle, (a) the expandable extraventricular receptacle undergoes anincrease in volume when exposed to a change in internal pressure from 10mmHg to 120 mmHg that is at least three times greater than (b) anincrease in volume that the flexible intraventricular receptacleundergoes when exposed to a change in internal pressure from 10 mmHg to120 mmHg.

In an application, the expandable extraventricular receptacle and theflexible intraventricular receptacle are configured such that, in theabsence of any external forces applied to the expandableextraventricular receptacle and the flexible intraventricularreceptacle, (a) the expandable extraventricular receptacle undergoes anincrease in volume when exposed to a change in internal pressure from 10mmHg to 120 mmHg that is at least 200%, and (b) the flexibleintraventricular receptacle undergoes an increase in volume when exposedto a change in internal pressure from 10 mmHg to 120 mmHg that is lessthan 120%.

There is also provided, in accordance with an application of the presentinvention a method for repairing a heart, including:

identifying a heart of a patient as having a reduced ejection fraction;and

in response to the identifying, reducing wall stress of a ventricle ofthe heart by implanting apparatus that facilitates cyclical moving offluid that is not blood of the patient into and out of the ventricle ofthe heart, the moving including:

-   -   during ventricular diastole, moving a volume of the fluid into        the ventricle in a manner that produces a corresponding decrease        in a total volume of blood that fills the ventricle during        diastole; and    -   during ventricular systole, moving the volume of the fluid out        of the ventricle in a manner that produces a corresponding        decrease in a total volume of the ventricle during isovolumetric        contraction of the ventricle.

In an application, implanting the apparatus includes reducing a volumeof blood expelled by the ventricle during systole.

In an application, moving the volume of the fluid out of the ventricleincludes moving the volume of the fluid out of the heart.

In an application, implanting the apparatus includes implantingapparatus including a bag, a compliant balloon and a conduit disposedbetween and in fluid communication with the bag and the compliantballoon, in a manner in which (1) the bag is disposed within theventricle, and (2) the compliant balloon is disposed outside theventricle.

In an application, wall compliance of the balloon is at least threetimes wall compliance of the bag.

In an application, the bag is noncompliant.

In an application, implanting the apparatus includes positioning the bagin a left ventricle.

In an application, implanting the apparatus includes positioning the bagin a right ventricle.

In an application, implanting the apparatus includes:

positioning the balloon at an extracardiac space, and

positioning the conduit transmyocardially.

In an application, implanting the apparatus includes positioning theballoon in a right atrium, and the method further includes implantingthe apparatus in a manner in which the conduit extends from the leftventricle to the right atrium.

In an application, implanting the apparatus includes positioning theballoon in a superior vena cava, and the method further includesimplanting the apparatus in a manner in which the conduit extends fromthe left ventricle to the superior vena cava.

In an application, implanting the apparatus includes positioning theballoon in an inferior vena cava, and the method further includesimplanting the apparatus in a manner in which the conduit extends fromthe left ventricle to the inferior vena cava.

In an application, implanting apparatus includes implanting apparatusincluding a first bag, a second bag and a conduit disposed between andin fluid communication with the first bag and the second bag, in amanner in which (1) the first bag is disposed within the ventricle, and(2) the second bag is disposed outside the ventricle.

In an application, the first and second bags are noncompliant.

In an application, implanting the apparatus includes positioning thefirst bag in a left ventricle.

In an application, implanting the apparatus includes positioning thefirst bag in a right ventricle.

In an application, implanting the apparatus includes:

positioning the second bag at an extracardiac space, and

positioning the conduit transmyocardially.

In an application, implanting the apparatus includes positioning thesecond bag in a right atrium, and the method further includes implantingthe apparatus in a manner in which the conduit extends from the leftventricle to the right atrium.

In an application, implanting the apparatus includes positioning thesecond bag in a superior vena cava, and the method further includesimplanting the apparatus in a manner in which the conduit extends fromthe left ventricle to the superior vena cava.

In an application, implanting the apparatus includes positioning thesecond bag in an inferior vena cava, and the method further includesimplanting the apparatus in a manner in which the conduit extends fromthe left ventricle to the inferior vena cava.

In an application, the apparatus includes an energy-storage elementcoupled to the second bag and configured to:

-   -   absorb energy upon filling of the second bag from a first state        to a second, expanded state, and    -   release the energy to return the second bag from the second,        expanded state to the first state.

In an application, the energy-storage element includes a plurality ofstruts surrounding the second bag, a respective portion of each of thestruts is configured to:

assume a longitudinally-elongated state upon the filling of the secondbag from the first state to the second, expanded state,

assume a longitudinally-shortened state, and

return the second bag from the second, expanded state to the first stateduring a transition of the energy-storage element from thelongitudinally-elongated state toward the longitudinally-shortenedstate.

In an application, the energy-storage element includes a mesh having afirst portion surrounding the second bag, the first portion of the meshis configured to:

absorb the energy upon the filling of the second bag from the firststate to the second, expanded state, and

release the energy to return the second bag from the second, expandedstate to the first state.

In an application, the second bag includes a bellows, and theenergy-storage element is coupled to the bellows.

In an application, implanting the apparatus includes acutely furtherreducing the ejection fraction and chronically increasing the ejectionfraction.

There is further provided, in accordance with an application of thepresent invention apparatus, including:

an intraventricular bag configured to be positioned within a ventricleof a heart of a patient, the bag having, in the absence of any externalforces applied thereto: (a) a first intraventricular bag volume when thebag has an internal pressure of 120 mmHg, and (b) a secondintraventricular bag volume when the bag has an internal pressure of 10mmHg, the first intraventricular bag volume being less than 110% of thesecond intraventricular bag volume;

an extraventricular bag configured to be positioned outside of theventricle, the extraventricular bag having, in the absence of anyexternal forces applied thereto: (a) a first extraventricular bag volumewhen the extraventricular bag has an internal pressure of 120 mmHg, and(b) a second extraventricular bag volume when the extraventricular baghas an internal pressure of 10 mmHg, the first extraventricular bagvolume being at least 200% of the second extraventricular bag volume;

a conduit disposed between and in fluid communication with theintraventricular bag and the extraventricular bag, the apparatus therebydefining a total internal space disposed within the conduit, theintraventricular bag, and the extraventricular bag; and

disposed within the internal space, 10-80 ml of fluid that is (a) notblood and (2) passable between the intraventricular bag and theextraventricular bag via the conduit,

the apparatus is configured such that:

-   -   during ventricular diastole, the extraventricular bag expels the        fluid, through the conduit, and into the intraventricular bag,        and    -   during ventricular systole, while an aortic valve of the heart        is closed, a volume of the fluid is expelled from the        intraventricular bag, through the conduit, into the        extraventricular bag, and

the apparatus further includes an energy-storage element coupled to theextraventricular bag and configured to:

-   -   absorb energy upon filling of the extraventricular bag from a        first state to a second, expanded state, and    -   release the energy to return the extraventricular bag from the        second, expanded state to the first state.

In an application, the extraventricular receptacle is configured to bepositioned at an extracardiac location, and the conduit defines atransmyocardial conduit configured to be disposed passing through a wallof the heart.

In an application, the energy-storage element includes a plurality ofstruts surrounding the extraventricular bag, a respective portion ofeach of the struts is configured to:

assume a longitudinally-elongated state upon the filling of theextraventricular bag from the first state to the second, expanded state,

assume a longitudinally-shortened state, and

return the extraventricular bag from the second, expanded state to thefirst state during a transition of the energy-storage element from thelongitudinally-elongated state toward the longitudinally-shortenedstate.

In an application, the energy-storage element includes a mesh having afirst portion surrounding the extraventricular bag, the first portion ofthe mesh is configured to:

absorb the energy upon the filling of the extraventricular bag from thefirst state to the second, expanded state, and

release the energy to return the extraventricular bag from the second,expanded state to the first state.

In an application, the extraventricular bag includes a bellows, and theenergy-storage element is coupled to the bellows in a manner in whichthe bellows is disposed between the first bag and the energy-storageelement.

In an application, the energy-storage element is configured to:

assume a compressed, longitudinally-shortened state upon the filling ofthe bellows from the first state to the second, expanded state, and

return the bellows from the second, expanded state to the first state.

In an application, the energy-storage element includes a coil spring.

In an application, the extraventricular bag includes a bellows, and theenergy-storage element is coupled to the bellows by surrounding thebellows at least in part.

In an application, the energy-storage element includes a coil springthat at least partially surrounds the bellows and is configured to:

assume a longitudinally-elongated state upon the filling of the bellowsfrom the first state to the second, expanded state, and

return the bellows from the second, expanded state to the first state.

In an application, the coil spring wraps around the bellows betweenfolds of the bellows.

There is also provided, in accordance with an application of the presentinvention apparatus, including:

a first bag having, in the absence of any external forces appliedthereto: (a) a first first-bag volume when the first bag has an internalpressure of 120 mmHg, and (b) a second first-bag volume when the firstbag has an internal pressure of 10 mmHg, the first first-bag volumebeing less than 110% of the second first-bag volume;

a second bag having, in the absence of any external forces appliedthereto: (a) a first second-bag volume when the second bag has aninternal pressure of 120 mmHg, and (b) a second second-bag volume whenthe second bag has an internal pressure of 10 mmHg, the first second-bagvolume being less than 110% of the second second-bag volume;

an energy-storage element coupled to the second bag and configured to:

-   -   absorb energy upon filling of the second bag from the first        second-bag volume to the second second-bag volume, and    -   release the energy to return the second bag from the second        second-bag volume to the first second-bag volume;

a conduit disposed between and in fluid communication with the first bagand the second bag, the apparatus thereby defining a total internalspace disposed within the conduit, the first bag, and the second bag;and

disposed within the internal space, 10-80 ml of fluid that is (a) notblood and (b) passable between the first bag and the second bag via theconduit.

In an application, the second bag is configured to be positioned at anextracardiac location, and the conduit defines a transmyocardial conduitconfigured to be disposed passing through a wall of the heart.

In an application, the energy-storage element includes a plurality ofstruts surrounding the second bag, a respective portion of each of thestruts is configured to:

assume a longitudinally-elongated state upon the filling of the secondbag from the first state to the second, expanded state,

assume a longitudinally-shortened state, and

return the second bag from the second, expanded state to the first stateduring a transition of the energy-storage element from thelongitudinally-elongated state toward the longitudinally-shortenedstate.

In an application, the energy-storage element includes a mesh having afirst portion surrounding the second bag, the first portion of the meshis configured to:

absorb the energy upon the filling of the second bag from the firststate to the second, expanded state, and

release the energy to return the second bag from the second, expandedstate to the first state.

In an application, the second bag includes a bellows, and theenergy-storage element is coupled to the bellows in a manner in whichthe bellows is disposed between the first bag and the energy-storageelement.

In an application, the energy-storage element is configured to:

assume a compressed, longitudinally-shortened state upon the filling ofthe bellows from the first state to the second, expanded state, and

return the bellows from the second, expanded state to the first state.

In an application, the energy-storage element includes a coil spring.

In an application, the second bag includes a bellows, and theenergy-storage element is coupled to the bellows by surrounding thebellows at least in part.

In an application, the energy-storage element includes a coil springthat at least partially surrounds the bellows and is configured to:

assume a longitudinally-elongated state upon the filling of the bellowsfrom the first state to the second, expanded state, and

return the bellows from the second, expanded state to the first state.

In an application, the coil spring wraps around the bellows betweenfolds of the bellows.

The present invention will be more fully understood from the followingdetailed description of applications thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-B are schematic illustrations of a passive pump comprising anoncompliant bag and a compliant balloon, in accordance with respectiveapplications of the present invention;

FIG. 2 is a schematic illustration of implantation of the passive pump,in accordance with some applications of the present invention;

FIGS. 3A-G are schematic illustrations of the operation of the passivepump, in accordance with some applications of the present invention;

FIG. 4A is a graph and FIG. 4B is a table representing the associationbetween the cardiac cycle and operation of the passive pump as shown inFIGS. 3A-G, in accordance with some applications of the presentinvention;

FIG. 5 is a schematic illustration of a port system connected to thepassive pump, in accordance with some applications of the presentinvention;

FIGS. 6A-B are schematic illustrations of a passive pump comprising twononcompliant bags and a spring, in accordance with some applications ofthe present invention;

FIGS. 7A-B, 8, and 9 are schematic illustrations of the operation of apassive pump, in accordance with respective applications of the presentinvention;

FIG. 10 is a pressure/volume graph illustrating the respectivepressure/volume loops of a failing heart, a healthy heart, and a heartwith the passive pump, in accordance with some applications of thepresent invention;

FIG. 11 is a schematic illustration of the operation of a passive pump,in accordance with some applications of the present invention;

FIGS. 12A-B are schematic illustrations of a passive pump comprising twononcompliant bags and a spring comprising a plurality of struts, inaccordance with some applications of the present invention;

FIGS. 13A-B are schematic illustrations of a passive pump comprising twononcompliant bags and braided mesh, in accordance with some applicationsof the present invention;

FIGS. 14A-B are schematic illustrations of a passive pump comprising twononcompliant bags and bellows coupled to a spring, in accordance withsome applications of the present invention; and

FIGS. 15A-B are schematic illustrations of a passive pump comprising twononcompliant bags and bellows surrounded by a spring, in accordance withsome applications of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIG. 1A, which is a schematic illustration of asystem 20 comprising a passive pump 21 which comprises a noncompliantbag 22 and a compliant balloon 24, in accordance with some applicationsof the present invention. A conduit 26 is disposed between and in fluidcommunication with bag 22 and compliant balloon 24. Passive pump 21defines a total internal space disposed within conduit 26, bag 22, andcompliant balloon 24. Fluid is disposed within the internal space and ispassable between bag 22 and compliant balloon 24 via conduit 26.Typically, the internal space contains 10-80 ml of fluid, e.g., 20-40 mlof fluid. Typically, the fluid comprises fluid that is not blood of thepatient. For some applications of the present invention, the fluidcomprises a gas, such as carbon dioxide, or a liquid, such as saline.Alternatively or additionally, the fluid comprises a reduced-osmolarityfluid, e.g., a contrast-agent fluid which is used for imaging and isknown to be acceptable for use in contact with blood of a patient. (Itis expected that in general, there will be no contact between the fluidand the patient's blood.)

Bag 22 comprises a noncompliant, biocompatible material, e.g.,polyethylene terephthalate (PET). Balloon 24 comprises a compliant,biocompatible material, e.g., polyolefin copolymer (POC), silicone, orpolyurethane. For some applications of the present invention, wallcompliance of the balloon 24 is at least three times wall compliance ofbag 22.

Passive pump 21 is configured for implantation at a heart of a patient.Typically, bag 22 is designated for positioning within a ventricle ofthe patient. For some applications, bag 22 is designated for positioningwithin a left ventricle of the heart of the patient. Alternatively, bag22 is designated for positioning within a right ventricle of the heartof the patient. Thus, bag 22 defines a flexible, intraventricularreceptacle. Balloon 24 is designated for positioning outside of theventricle. For some applications, balloon 24 is designated forpositioning outside of the heart of the patient. In such applications,balloon 24 defines an expandable extracardiac receptacle, and conduit 26defines a transmyocardial conduit disposed between and in fluidcommunication with the flexible intraventricular receptacle (e.g., bag22) and the expandable extracardiac receptacle (e.g., balloon 24). Forapplications in which conduit 26 is positioned transmyocardially, asshown in FIGS. 2, 3A-G, and 5, conduit 26 typically has an innerdiameter of 6-10 mm, and a length of 2-5 cm, e.g., 3 cm.

For some applications, balloon 24 is designated for positioning outsideof the ventricle of the heart of the patient (e.g., in the right atriumas shown in FIGS. 7A-B, for example, in the superior vena cava, as shownin FIG. 8, for example, or in the inferior vena cava, as shown in FIG.9, for example). In such applications, balloon 24 defines an expandableextraventricular receptacle, and conduit 26 defines a conduit disposedbetween and in fluid communication with the flexible intraventricularreceptacle (e.g., bag 22) and the expandable extraventricular receptacle(e.g., balloon 24).

For some applications, balloon 24 is configured to be positioned at asite within the patient's vascular system, e.g., in a right atrium ofthe heart of the patient, or in the patient's superior vena cava orinferior vena cava, as shown in FIGS. 7A-B, 8 and 9.

That is, for generally all applications of the present invention,balloon 24 of FIGS. 1A-3G and 5 defines an extraventricular receptacle.

Reference is now made to FIGS. 1A-B, 2, 3A-G, 4A-B, 5, 6A-B, 7A-B, 8-11,12A-B, 13A-B, 14A-B, and 15A-B. Passive pumps 21, 42, 82, 92, 182, 202,302, 402, and 502 are configured for facilitating reverse remodeling inthe heart of a patient experiencing heart failure. Passive pumps 21, 42,82, 92, 182, 202, 302, 402, and 502 are configured, during ventricularsystole, while an aortic valve of the heart is closed, for enablingpassage of fluid that is not blood of the patient from within theventricle to outside of the ventricle in a manner that produces acorresponding decrease in a total volume of the ventricle duringisovolumetric contraction of the ventricle. That is, for example, sincepassive pump 21 is passive and bag 22 is noncompliant, some volume ofthe fluid exits the ventricle by exiting bag 22 during ventriculardiastolic filling, such that pressure in the heart begins to rise at alower total volume of the ventricle at the onset of isovolumetriccontraction of the ventricle. Ultimately, passive pumps 21, 42, 82, 92,182, 202, 302, 402, and 502 enable reverse remodeling of the heartbecause the left ventricle does not undergo as high wall stress whilecontaining a high volume of blood, at the onset of and/or duringisovolumetric contraction of the ventricle, as would occur in theabsence of the applications of the present invention described herein.

Passive pumps 21, 42, 82, 92, 182, 202, 302, 402, and 502 are passive inthat their respective systems 20, 40, 60, 90, 100, 120, 180, 200, 300,400, and 500 do not require any electrical or other source of power forthe passive pumps to move the fluid within the pump. Additionally,passive pumps 21, 42, 82, 92, 182, 202, 302, 402, and 502 do notfacilitate acute therapeutic motion of the ventricular wall, and do notacutely therapeutically push the ventricular wall, myocardium and/or theepicardium with a force originated due to energy harvested by the systemfrom a motion of the ventricular chamber. Rather, passive pumps 21, 42,82, 92, 182, 202, 302, 402, and 502 function responsively to a cardiaccycle of the heart in a manner in which, for example:

-   -   at the onset of and during ventricular diastole, due to        decreased pressure in the left ventricle, the extraventricular        receptacle (e.g., balloon 24) contracts (as shown in the upper        figure in FIG. 1A, for example) and begins to expel the fluid,        through the conduit (e.g., the transmyocardial conduit, for        example conduit 26), into the intraventricular receptacle (e.g.,        bag 22), and    -   during ventricular systole, and even slightly before, while the        aortic valve of the heart is closed, a volume of the fluid is        expelled from the intraventricular receptacle (e.g., bag 22),        through the conduit (e.g., the transmyocardial conduit, for        example conduit 26), into the extraventricular receptacle (e.g.,        balloon 24), in a manner that produces a corresponding decrease        in a total volume of the ventricle during isovolumetric        contraction of the ventricle.

Thus, due to the cyclical moving of fluid that is not blood into and outof the ventricle, passive pumps 21, 42, 82, 92, 182, 202, 302, 402, and502 cause acute as well as chronic reduction in wall stress of cardiacmuscle surrounding the ventricle at the onset of ventricular systole.Additionally, for some embodiments of the present invention, passivepumps 21, 42, 82, 92, 182, 202, 302, 402, and 502 also cause theejection fraction of the heart and the cardiac output to be (1) evenfurther acutely reduced in patients that have been identified as alreadyhaving a reduced ejection fraction and cardiac output, and (2)chronically increased. At the onset of and during ventricular diastole,systems 20, 40, 60, 90, 100, 120, 180, 200, 300, 400, and 500 enable themoving of a volume of the fluid within passive pumps 21, 42, 82, 92,182, 202, 302, 402, and 502 into the ventricle in a manner that producesa corresponding decrease in a total volume of blood that fills theventricle during diastole. During ventricular systole and even slightlybefore, systems 20, 40, 60, 90, 100, 120, 180, 200, 300, 400, and 500enable moving the volume of the fluid within the pump out of theventricle in a manner that produces a corresponding decrease in a totalvolume of the ventricle during isovolumetric contraction of theventricle.

FIG. 1A shows passive pump 21 in a state in which fluid is distributedin a manner in which fluid is passed into bag 22 such that bag 22assumes a larger volume (upper image) than when the fluid is passed outof bag 22 and into balloon 24 (lower image) so that bag 22 assumes alower volume. As fluid passes out of bag 22 and into balloon 24, balloon24 fills and/or expands to assume a larger volume (lower image) thanwhen less fluid is disposed within balloon 24 (upper image). Sinceballoon 24 is compliant, it contracts to expel fluid disposed therein.Typically, one or more of the following numerical characteristicsapplies to bag 22 and balloon 24:

-   -   In the absence of external force applied to balloon 24 (e.g.,        the expandable extraventricular receptacle) and bag 22 (e.g.,        the flexible intraventricular receptacle), balloon 24 typically        undergoes an increase in volume when exposed to a change in        internal pressure from 10 mmHg to 120 mmHg that is at least        three (e.g., at least five) times greater than any increase in        volume that bag 22 undergoes when exposed to a change in        internal pressure from 10 mmHg to 120 mmHg    -   In the absence of any external forces applied to balloon 24        (e.g., expandable extraventricular receptacle) and to bag 22        (e.g., the flexible intraventricular receptacle), (a) balloon 24        undergoes an increase in volume when exposed to a change in        internal pressure from 10 mmHg to 120 mmHg that is at least        200%, and (b) (i) the volume of bag 22 having 120 mmHg internal        pressure is less than (ii) a volume that is greater than 20%        more than the volume of bag 22 having 10 mmHg internal pressure        (and is for some applications substantially the same as the        volume of bag 22 having 10 mmHg internal pressure).    -   In the absence of any external forces applied to bag 22, (a) a        first bag volume of bag 22 is 10-80 ml (e.g., 40 ml) when the        intraventricular receptacle has an internal pressure of 120        mmHg, and (b) a second bag volume of bag 22 is 10-80 ml (e.g.,        40 ml) when the bag has an internal pressure of 10 mmHg.        Additionally, the first bag volume is less than 110% of the        second bag volume. The second bag volume is typically within 10%        of the first bag volume, e.g., the first and second bag volumes        are substantially the same, because bag 22 is non-compliant.    -   In the absence of any external forces applied to balloon 24,        balloon 24 has (a) a first balloon volume of at least 30 ml,        e.g., 80 ml, when balloon 24 has an internal pressure of 120        mmHg, and (b) a second balloon volume of at least 10 ml, e.g.,        20 ml, when balloon 24 has an internal pressure of 10 mmHg.

It is to be noted that the passage of a given volume of fluid out of bag22 corresponds to a similar or identical passage of fluid into balloon24 and vice versa. That is, a volume increase in one receptaclesubstantially corresponds to a volume decrease in another receptacle.

Since bag 22 is configured for positioning within the ventricle, bag 22is subjected to high pressure from the ventricle. As such, a fixationrod 28 is typically disposed within bag 22 which reinforces bag 22 andprevents everting and/or migration of bag 22 out of the ventricle. Forsome applications of the present invention, rod 28 is part of ascaffolding 29 disposed within bag 22. For some applications of thepresent invention, rod 28 prevents everting of bag 22 through thetransmyocardial access point of passive pump 21 to the ventricle. Forsome applications in which balloon 24 is positioned outside of theheart, balloon 24 may be surrounded by an optional cage (not shown). Thecage may help protect balloon 24 by encasing balloon 24 or it may helpfacilitate expansion of balloon 24 by providing a defined space in whichballoon 24 is allowed to expand.

Conduit 26 is reinforced, e.g., by being surrounded or internally lined,by a stent structure 30. Structure 30 comprises a central tubularsubstructure 36, a first flared section 32 which is configured tosurround a portion of bag 22, and a second flared section 34 which isconfigured to surround a portion of balloon 24.

For applications in which conduit 26 is configured to be positionedwithin tissue of the patient, e.g., within myocardial tissue, conduit 26comprises a tube surrounded by porous material, e.g., a fabric, whichfacilitates tissue growth around conduit 26 in order to enable sealingof conduit 26 and inhibit leakage of blood out of the ventricle. Forsome applications of the present invention, conduit 26 self-expands toposition itself within the tissue of the patient.

Reference is now made to FIG. 1B, which is a schematic illustration of asystem 40 comprising a passive pump 42 which comprises a noncompliantbag 22 and a compliant balloon 24, in accordance with some applicationsof the present invention. A conduit 26 is disposed between and in fluidcommunication with bag 22 and compliant balloon 24. Passive pump 42defines a total internal space disposed within conduit 26, bag 22, andcompliant balloon 24. Fluid is disposed within the internal space and ispassable between bag 22 and compliant balloon 24 via conduit 26. It isto be noted that system 40 is similar to and used in a similar fashionas system 20 described hereinabove with reference to FIG. 1A, likereference numbers referring to like parts, with the exception thatpassive pump 42 does not comprise rod 28 and scaffolding 29.

FIG. 2 is a schematic illustration of implantation passive pump 21 ofFIG. 1A, in accordance with some applications of the present invention.Typically, passive pump 21 is delivered transapically for applicationsin which passive pump 21 is configured to be positionedtransmyocardially such that bag 22 is positioned within a ventricle 50while balloon 24 is positioned at an extracardiac location. For someapplications, passive pump 21 is delivered using a sub-xyphoid approach.Passive pump 21 is delivered to the heart in a compressed state within adelivery tool 58. A distal portion of delivery tool 58 is passed throughmyocardial tissue 53 at apex 51 of the heart. Delivery tool 58 enablesbag 22 to be positioned within a space of ventricle 50. Tool 58 pushespassive pump 21 distally and/or tool 58 is retracted proximally in orderto expose flared section 32 of stent structure 30 such that flaredsection 32 expands against and engages a wall of ventricle 50. For someapplications, flared section 32 comprises a biocompatible material iscoated with a porous material, e.g., a fabric, which helps facilitatesealing of flared section 32 with respect to cardiac tissue by enhancingtissue growth into the outer surface of flared section 32. Flaredsection 32 facilitates fixation of bag 22 in ventricle 50. Flaredsection 32 is shaped so as to allow for bag 22 to fill and take shape asshown in the upper figure of FIG. 1A. Tool 58 is then further retractedso that central tubular substructure 36 expands within and engagesmyocardial tissue 53. Central tubular substructure 36 comprises abiocompatible material surrounded by porous material, e.g., a fabric,which helps facilitate sealing of central tubular substructure 36 withrespect to cardiac tissue by enhancing tissue growth into substructure36. Tool 58 is then yet further retracted, so that flared section 34expands against and engages the epicardium of the heart. For someapplications, flared section 34 comprises a biocompatible materialcoated by a porous material, e.g., a fabric, which helps facilitatesealing of flared section 34 with respect to cardiac tissue by enhancingtissue growth into flared section 34. Flared section 34 facilitatesfixation of balloon 24 at the extracardiac location. Flared section 34is shaped so as to allow for balloon 24 to fill, expand, and take shapeas shown in the lower figure of FIG. 1A.

Reference is now made to FIGS. 3A-G, which are schematic illustrationsof the operation of passive pump 21 of FIG. 1A, in accordance with someapplications of the present invention. Passive pump 42 operates in alike manner.

Reference is now made to FIG. 4A, which is a graph and to FIG. 4B, whichis a table representing the association between the cardiac cycle andoperation of passive pump 21 as shown in FIGS. 3A-G, as well as passivepumps 42, 82, 92, 182, 202, 302, 402, and 502, mutatis mutandis, inaccordance with some applications of the present invention.

FIG. 3A shows a Stage A in which the heart undergoes isovolumetricrelaxation while mitral valve 54 is closed and aortic valve 56 isclosed. Stage A is when the heart undergoes diastole and blood has notyet entered left ventricle 50. The volume in ventricle 50 is low and thepressure decreases. At Stage A, pressure in ventricle 50 is stillsufficiently high (as shown in the near-bottom left side of the graph inFIG. 4A) that fluid from within passive pump 21 does not yet enter bag22 disposed within ventricle 50 and remains within balloon 24 in itsexpanded state. Balloon 24 assumes a volume in its expanded state of forexample 20-80 ml, e.g., 40 ml. As shown in FIG. 3A, bag 22 assumes avery low volume and is near to empty or empty of the fluid. Rod 28 andscaffolding 29 maintain bag 22 from escaping from ventricle 50 byeverting through myocardial tissue 53.

Once the pressure in ventricle 50 drops to Stage B as represented inFIG. 3B and in the bottom left corner of the graph on FIG. 4A, balloon24 contracts due to its compliance and due to the reduced pressure inventricle 50, and expels the fluid through transmyocardial conduit 26and into bag 22 within left ventricle 50. Bag 22 fills to assume agreater volume than the volume it assumes in Stage A. Bag 22 fills to avolume of 20-80 ml, e.g., 40 ml. As shown in FIG. 3B, balloon 24 has avery low volume and is near to empty or empty of the fluid.

Since (1) passive pump 21 is constructed in a manner in which bag 22comprises a noncompliant material and balloon 24 is compliant, and (2)fluid passes between balloon 24 into bag 22 responsively to changes inpressure within ventricle 50, passive pump 21 operates passively and inresponse to the cardiac cycle.

At Stage B, the heart is in diastole, and mitral valve 54 begins to openand blood begins to enter left ventricle 50 from left atrium 52. Aorticvalve 56 remains closed. Bag 22, in its filled state, occupies spacewithin ventricle 50 while blood of the patient fills ventricle 50.Moving the volume of the fluid into ventricle 50, i.e., into bag 22,produces a corresponding decrease in a total volume of blood that fillsventricle 50 during diastole as is shown in FIG. 3C.

FIG. 3C shows Stage C, in which the diastolic phase is near completionand mitral valve 54 begins to close. Aortic valve 56 remains closed.Ventricle 50 is close to full with blood. Due to the volume of blood inventricle 50, some of the fluid within bag 22 is pushed into balloon 24.At Stage C, the pressure in ventricle 50 is increased more than thepressure at Stage B.

Reference is now made to FIG. 3D, which shows the heart in a stage ofisovolumetric contraction at the onset of systole. Both aortic valve 56and mitral valve 54 are closed. Once mitral valve 54 is closed, thepressure due to the volume of blood in ventricle 50 and ventricularcontraction pushes the fluid from bag 22 into balloon 24, such that bag22 decreases in volume and balloon 24 increases in volume. Thus,pressure in ventricle 50 forces the fluid from within bag 22 throughconduit 26 and into balloon 24. Movement of the volume of fluid out ofthe heart and into balloon 24 produces a corresponding decrease in atotal volume of ventricle 50 during isovolumetric contraction ofventricle 50. It is advantageous to reduce the volume of ventricle 50during isovolumetric contraction of ventricle 50 in order to facilitatereverse remodeling of the ventricle such that the heart returns to ahealthy geometry. Reducing the volume of ventricle 50 increase theventricular wall thickness during contraction, thereby reducing wallstress in the ventricle wall. The reduced stress on the ventricle wallenables the wall to gradually return to its normal non-stretchedgeometry, i.e., to undergo reverse remodeling.

That is, with reference to the graph of FIG. 4A, the pressure of theventricle isovolumetrically increases at a lower volume (as depicted bythe dotted line representing the device-adjusted PV loop) rather than ata higher volume (as depicted by the solid line representing the normalPV loop). Lower volume during contraction yields less exertion per cubicmillimeter of ventricular wall tissue, enabling the heart to heal andreverse-remodel. Thus, without the assistance of the passive pumpsdescribed herein, the pathologically remodeled heart would otherwisefollow the graph represented by the solid line; that is, ventricle 50would begin increasing in pressure during the isovolumetric phase ofsystole at a greater volume of ventricle 50, thereby increasing stressin tissue of the ventricle wall. However, with the assistance of thepassive pumps 21, 42, 82, 92, 182, 202, 302, 402, and 502, theremodeled, stretched ventricle 50 instead follows the graph representedby the dotted line; that is, ventricle 50 begins increasing in pressureduring the isovolumetric phase of systole at a lower volume of ventricle50, thereby reducing the stress on tissue of the ventricle wall. Thus,the assistance of passive pumps 21, 42, 82, 92, 182, 202, 302, 402, and502 generates acute as well as chronic reduction in wall stress ofcardiac muscle surrounding the ventricle at the onset of ventricularsystole due to cyclical moving of fluid that is not blood of the patientinto and out of ventricle 50, i.e., into and out of bag 22 and balloon24 of passive pumps 21, 42, 82, 92, 182, 202, 302, 402, and 502.Additionally, for some embodiments of the present invention, passivepumps 21, 42, 82, 92, 182, 202, 302, 402, and 502 also generate (1) anacute further reducing of the ejection fraction of the heart due tocyclical moving of fluid that is not blood of the patient into and outof ventricle 50, i.e., into and out of the intraventricular receptacleand the extraventricular receptacle of passive pumps 21, 42, 82, 92,182, 202, 302, 402, and 502 as well as (2) a chronic increase inejection fraction. This acute further reduction of the ejection fractionreduces the stress on the ventricle.

In FIG. 3E, left ventricle 50 increases in pressure and continuesisovolumetric contraction while mitral valve 54 and aortic valve 56remain closed in Stage E. The increase in pressure in ventricle 50together with the ventricle having filled with blood pushes theremaining fluid out of bag 22 and through conduit 26 and into balloon 24in a manner in which bag 22 is near to empty or empty. Balloon 24 fillsto hold the volume of fluid that was occupying space in ventricle 50(FIGS. 3B-D) just before the onset of isovolumetric contraction. Movingthe volume of fluid out of ventricle 50 produces a correspondingdecrease in volume of ventricle 50 during isovolumetric contraction.

In Stage F as shown in FIG. 3F, aortic valve 56 opens and the ejectionstage of systole commences while the pressure in ventricle 50 increasesdue to the contraction of ventricle 50 in order to eject the blood. Alower volume of blood passes through aortic valve 56 during ejectionthan would otherwise pass through valve 56 in the absence of passivepump 21.

At the end of systole, as shown in Stage G of FIG. 3G, the blood hasbeen ejected from ventricle 50, however, the pressure in ventricle 50 isstill high such that the fluid remains in balloon 24. Aortic valve 56 isclosed and the heart initiates isovolumetric relaxation. Once ventricle50 sufficiently reduces in pressure during the isovolumetric relaxationstage of diastole, the heart returns to Stage A shown in FIG. 3A. Oncethe pressure in ventricle is low enough (Stage B of FIGS. 3B and 4A),balloon 24 contracts due to its compliance and expels the fluid backinto bag 22 (FIG. 3B), and the cycle repeats.

Reference is now made to FIG. 5, which is a schematic illustration of asystem 60 comprising a port 64 connected to passive pump 21 of FIG. 1A,in accordance with some applications of the present invention. Port 64comprises a typically subcutaneous port which enables the physician tocontrol a volume of fluid in passive pump 21. For some applications ofthe present invention, passive pump 21 is implanted without any fluid,and the operating physician injects fluid into passive pump 21 via port64. For other applications, passive pump 21 is implanted with fluid andsystem 60 enables the physician to inject and/or extract fluid dependingon the need of the patient. Port 64 comprises a membrane that ispenetrable by a needle connected to a syringe 66 filled with fluiddesignated for injection through port 64, through a tube 62 connectingport 64 to passive pump 21 and into the internal space defined bypassive pump 21. For some applications (as shown), tube 62 is coupled toballoon 24 by way of illustration and not limitation. For example, tube62 may alternatively be connected to conduit 26 or to bag 22.

Port 64 may be placed subcutaneously at the waist of the patient asshown, or at any suitable location in the body of the patient, e.g., thechest.

For some applications, a pressure sensor 68 (e.g., coupled to tube 62)senses the pressure in passive pump 21 and wirelessly transmits to anexternal device 70 information relating to the pressure in passive pump21. Sensor 68 may be coupled to tube 62 at any suitable location alongtube 62 or to any portion of passive pump 21. For some applications ofthe present invention, a coil is coupled to sensor 68 for supplyingpower to sensor 68. For some applications of the present invention,sensor 68 is powered by radiofrequency or ultrasound energy. For someapplications, the pressure measurement happens when the patient is inthe doctor's office and the power antenna (e.g., radiofrequencytransmitter or ultrasound transmitter) is placed next to the patient'schest. Based on the reading from sensor 68, the physician decideswhether to add fluid to pump 21 or to remove fluid from pump 21.

For some applications of the present invention, two pressure sensors arecoupled to conduit 26, e.g., at either end of conduit 26 in order tomeasure flow through conduit 26. The two pressure sensors allow thephysician to derive the volume of each of bag 22 and balloon 24. Thatis, in response to calculation of the difference in pressure between thetwo sensors, the physician can determine in which of either receptaclethe pressure is higher. For example, if it is sensed and determined thatthe pressure in bag 22 is higher than the pressure in balloon 24, thenit can be determined that the flow is going from bag 22 to balloon 24.

Reference is now made to FIGS. 1A-5. It is to be noted that for someapplications, instead of comprising balloon 24 at the extraventricularlocation, passive pumps 21 and 42 may comprise a second noncompliant baghaving the same or similar properties as bag 22.

FIGS. 6A-B are schematic illustrations of a system 80 comprising apassive pump 82 comprising two bags 22 and 84 and an energy-storageelement 250 comprising a spring 86, in accordance with some applicationsof the present invention. It is to be noted that system 80 is similar tosystem 20 described hereinabove with reference to FIG. 1A, likereference numbers referring to like parts, with the exception thatpassive pump 82 does not comprise compliant balloon 24. Bags 22 and 84have similar wall compliance (for example, effectively no compliance atpressures less than 120 mmHg). For some applications, each of bags 22and 84 has, in the absence of any external forces applied thereto: (a) afirst volume when bags 22 and 84 each has an internal pressure of 120mmHg, and (b) a second volume when the bags 22 and 84 each has aninternal pressure of 10 mmHg, the first volume being less than 110% ofthe second volume.

Fluid is disposed within the internal space and is passable between bags22 and 84 via conduit 26. Typically, the internal space contains 10-80ml of fluid, e.g., 20-40 ml of fluid. Typically, the fluid comprisesfluid that is not blood of the patient. For some applications of thepresent invention, the fluid comprises a gas, such as carbon dioxide, ora liquid, such as saline.

It is to be noted that bag 84 has little to no wall compliance, however,the presence of energy-storage element 250 (e.g., spring 86) impartscompliance to the section of passive pump 82 that comprises bag 84 andenergy-storage element 250 (e.g., spring 86).

Spring 86 comprises two broad structural elements 85 that are coupledtogether by a spring hinge 87. Spring 86 is coupled to an externalsurface of bag 84. Spring 86 has an energy-storage state (FIG. 6A) uponbag 84 assuming a greater volume, and an energy-released state (FIG.6B).

Once the pressure in the ventricle decreases during diastole, spring 86releases the energy stored in it, expelling the fluid from within bag 84into bag 22. That is, spring 86 is configured to (1) absorb energy uponfilling of bag 84 (i.e., the extraventricular receptacle) from a firststate to a second, expanded state (FIG. 6A), and (2) release the energyto return bag 84 (i.e., the extraventricular receptacle) from thesecond, expanded state to the first state (FIG. 6B).

It is to be noted that spring 86 comprises structural elements 85 andhinge 87 by way of illustration and not limitation and that spring 86may comprise a spring having any suitable shape (e.g., helical).

Reference is now made to FIGS. 3A-G, 4A-B, and 6A-B. It is to be notedthat passive pump 82 as described with reference to FIGS. 6A-B operatesin Stages A-G as described in accordance with the operation of passivepump 21 with reference to FIGS. 3A-G, the graph of FIG. 4A, and thetable of FIG. 4B, mutatis mutandis. For such applications, bag 84 is anextraventricular receptacle.

Reference is now made to FIGS. 1A-3G, 5, and 6A-9. It is to be notedthat systems 20, 40, 60, 90, 100, and 120 may comprise energy-storageelements 250 described herein, and balloon 24 may comprise a bag such asa noncompliant bag. For example, e.g., the extraventricular receptaclemay be coupled to (1) spring 86, as described hereinabove with referenceto FIGS. 6A-B, (2) stent structure 250 a comprising a plurality ofstruts 206 as described hereinbelow with reference to FIGS. 12A-B, or(3) mesh 250 b as described hereinbelow with reference to FIGS. 13A-B.For other applications, the extraventricular receptacle may comprise abellows 406 or 506 coupled to coil springs 250 c and 250 d,respectively, as described hereinbelow with reference to FIGS. 14A-15B.

Reference is now made to FIGS. 7A-B, which are schematic illustrationsof a system 90 comprising a passive pump 92 in which a receptaclecomprising a bag 96 is positioned within left ventricle 50 and a secondreceptacle 94 is positioned in a right atrium 55, in accordance withsome applications of the present invention. Typically, a conduit 98connects bag 96 and receptacle 94. Conduit 98 passes through mitralvalve 54 and crosses the interatrial septum, e.g., via the fossa ovalisand into right atrium 55. Conduit 98 typically comprises a tube havingan inner diameter of at least 5 mm in order to allow for passing offluid between bag 96 and receptacle 94. For some applications of thepresent invention, passive pump 92 comprises stent structure 30surrounding the portion of conduit 98 designated for passing through theinteratrial septum or through the fossa ovalis (not shown). For someapplications, conduit 98 may comprise a tube covered in a porousmaterial, e.g., a fabric, which enhances ingrowth of tissue into theouter surface of conduit 98 in order to seal conduit 98 within theinteratrial septal tissue and prevent leaking.

For some applications, bag 96 is similar to or the same as bag 22described hereinabove with reference to FIGS. 1A-B, 2, 3A-G, 4A-B, 5,and 6A-B. That is, bag 96 is noncompliant.

For some applications, receptacle 94 is similar to or the same asballoon 24 described hereinabove with reference to FIGS. 1A-B, 2, 3A-G,4A-B, and 5. That is, receptacle 94 is compliant and has wallcompliance. Receptacle 94 is considered an extraventricular receptacle.

For some applications, receptacle 94 is similar to bag 22 describedhereinabove with reference to FIGS. 1A-B, 2, 3A-G, 4A-B, 5, and 6A-B orto bag 84 described hereinabove with reference to FIGS. 6A-B (evenwithout utilizing spring 86). That is, receptacle 94 is noncompliant. Insuch applications fluid passes from receptacle 94 to bag 96 disposedwithin left ventricle 50 when pressure in left ventricle 50 reduces fromaround 120 mmHg to around 5 mmHg. Since pressure in right atrium 55remains around 15 mmHg, when pressure in left ventricle 50 drops toaround 5 mmHg in Stage B (described hereinabove with reference to FIG.3B), for example, as shown in FIG. 7A, fluid passes from receptacle 94within right atrium 55 and into bag 96 disposed within left ventricle50.

In FIG. 7B, left ventricle 50 increases in pressure and continuesisovolumetric contraction while mitral valve 54 and aortic valve 56remain closed in Stage E (as described hereinabove with reference toFIG. 3E). The increase in pressure in ventricle 50 together with theventricle having filled with blood pushes the fluid out of bag 96 andthrough conduit 98 and into receptacle 94 in a manner in which bag 96 isnear to empty or empty. Receptacle 94 fills to hold the volume of fluidthat was occupying space in ventricle 50 (FIGS. 3B-D) just before theonset of isovolumetric contraction. Moving the volume of fluid out ofventricle 50 produces a corresponding decrease in volume of ventricle 50during isovolumetric contraction.

Reference is now made to FIGS. 3A-G, 4A-B, 7A-B, and 8-9. It is to benoted that passive pump 92 as described with reference to FIGS. 7A-B and8-9 operates in Stages A-G as described in accordance with the operationof passive pump 21 with reference to FIGS. 3A-G, the graph of FIG. 4A,and the table of FIG. 4B, mutatis mutandis.

Reference is now made to FIGS. 6A-B, 7A-B, 8-9, and 12A-15B. It is to benoted that systems 90, 100, and 120 may comprise energy-storage elements250 described herein (e.g., spring 86 coupled to receptacle 94 asdescribed hereinabove with reference to FIGS. 6A-B, stent structure 250a comprising a plurality of struts 206 as described hereinbelow withreference to FIGS. 12A-B, mesh 250 b as described hereinbelow withreference to FIGS. 13A-B, and coil springs 250 c and 250 d as describedhereinbelow with reference to FIGS. 14A-15B). Additionally, fluid isdisposed within the internal space and is passable between receptacle 94and bag 96 via conduit 98. Typically, the internal space contains 10-80ml of fluid, e.g., 20-40 ml of fluid. Typically, the fluid comprisesfluid that is not blood of the patient. For some applications of thepresent invention, the fluid comprises a gas, such as carbon dioxide, ora liquid, such as saline.

Reference is again made to FIGS. 7A-B. Passive pump 92 is implantedusing a transcatheter/transvascular approach and advantageously does notrequire making an incision in myocardial tissue of the heart of thepatient.

For some applications, conduit 98 travels from bag 96, through a holemade in the interventricular septum, through the tricuspid valve, and toreceptacle 94 positioned in right atrium 55.

Reference is now made to FIG. 8, which is a schematic illustration of asystem 100 comprising passive pump 92 in which bag 96 is positionedwithin left ventricle 50 and receptacle 94 is positioned in the superiorvena cava 102, in accordance with some applications of the presentinvention. Receptacle 94 is an extraventricular receptacle. It is to benoted that system 100 is similar to system 90 described hereinabove withreference to FIGS. 7A-B, like reference numbers referring to like parts,with the exception that passive receptacle 94 of pump 92 is positionedin superior vena cava 102.

Reference is now made to FIG. 9, which is a schematic illustration of asystem 120 comprising passive pump 92 in which bag 96 is positionedwithin left ventricle 50 and receptacle 94 is positioned in the inferiorvena cava 122, in accordance with some applications of the presentinvention. It is to be noted that system 120 is similar to system 90described hereinabove with reference to FIGS. 7A-B, like referencenumbers referring to like parts, with the exception that passivereceptacle 94 of pump 92 is positioned in inferior vena cava 122.Receptacle 94 is an extraventricular receptacle.

Reference is now made to FIGS. 7A-B and 8-9. It is to be noted that bag96 may be positioned within the right ventricle. It is to beadditionally noted that, for some applications, use of gas within pump92 may be preferable for embodiments in which pump 92 is positionedintravascularly.

Reference is now made to FIG. 10, which is a pressure/volume graphillustrating a pressure/volume loop 170 of a failing heart, apressure/volume loop 150 of a healthy heart, and a pressure/volume loop160 of a heart with the passive pumps described herein, in accordancewith some applications of the present invention. Pressure/volume loop170 of a failing heart shows reduced stroke volume increased leftventricular end-diastolic pressure and volume.

Reference is now made to FIGS. 1A-B, 2, 3A-G, 4A-B, 5, 6A-B, 7A-B, 8-11,12A-B, 13A-B, 14A-B, and 15A-B. Upon implantation of passive pumps 21,42, 82, 92, 182, 202, 302, 402, and 502 described herein, thepressure/volume curve shifts left (i.e., loop 160), resulting in anincrease in stroke volume and a decrease in end-diastolic pressure andend-diastolic volume as compared to loop 170. This shift in the looptoward loop 160 enables the heart to reverse remodel.

Reference is now made to FIG. 11, which is a schematic illustration of asystem 180 comprising a passive pump 182 in which a receptaclecomprising a bag 186 is positioned within left ventricle 50 and a secondreceptacle 184 is positioned subcutaneously, in accordance with someapplications of the present invention. Receptacle 184 is anextraventricular receptacle. For some applications, a pocket is createdsubcutaneously for receptacle 184 to be placed within. Typically, aconduit 188 connects bag 186 and receptacle 184. Conduit 188 passesthrough the mitral valve into left atrium 52, crosses the interatrialseptum, e.g., via the fossa ovalis, into right atrium 55, passes throughsuperior vena cava 102 and into a subclavian vein 190. Conduit 188 exitssubclavian vein 190 and passes to a subcutaneous location, e.g., near ashoulder, as shown, or any suitable subcutaneous location. Conduit 188typically comprises a tube having an inner diameter of at least 5 mm inorder to allow for passing of fluid between bag 186 and receptacle 184.For some applications of the present invention, passive pump 182comprises stent structure 30 (described hereinabove with reference toFIGS. 1A-B) surrounding the portion of conduit 188 designated forpassing through the interatrial septum or through the fossa ovalis (notshown). For some applications, conduit 188 comprises a tube surroundedby porous material, e.g., a fabric, which facilitates tissue growtharound conduit 188 in order to enable sealing of conduit 188 and inhibitleakage of blood out of the vasculature through which conduit passes,e.g., through the interatrial septum or through the passage created insubclavian vein 190. For some applications of the present invention,conduit 188 self-expands to position itself within openings created inthe vasculature through which the conduit passes, e.g., through theinteratrial septum or through the passage created in subclavian vein190.

For some applications, bag 186 is similar to or the same as bag 22described hereinabove with reference to FIGS. 1A-B, 2, 3A-G, 4A-B, 5,and 6A-B. That is, bag 186 is noncompliant.

For some applications, receptacle 184 is similar to or the same asballoon 24 described hereinabove with reference to FIGS. 1A-B, 2, 3A-G,4A-B, and 5. That is, receptacle 184 is compliant and has wallcompliance.

For some applications, receptacle 184 is similar to bag 22 describedhereinabove with reference to FIGS. 1A-B, 2, 3A-G, 4A-B, 5, and 6A-B orto bag 84 described hereinabove with reference to FIGS. 6A-B (evenwithout utilizing spring 86). That is, receptacle 184 is noncompliant.In such applications fluid passes from receptacle 184 to bag 186disposed within left ventricle 50 when pressure in left ventricle 50reduces from around 120 mmHg to around 5 mmHg Since pressure in thesubcutaneous location is higher than 5 mmHg, when pressure in leftventricle 50 drops to around 5 mmHg in Stage B (described hereinabovewith reference to FIG. 3B), fluid passes from receptacle 184 at thesubcutaneous location, and into bag 186 disposed within left ventricle50.

Once left ventricle 50 increases in pressure and continues isovolumetriccontraction while the mitral and aortic valves remain closed in Stage E(as described hereinabove with reference to FIG. 3E), the increase inpressure in ventricle 50 together with the ventricle having filled withblood pushes the fluid out of bag 186 and through conduit 188 and intoreceptacle 184 in a manner in which bag 186 is near to empty or empty.Receptacle 184 fills to hold the volume of fluid that was occupyingspace in ventricle 50 (FIGS. 3B-D) just before the onset ofisovolumetric contraction. Moving the volume of fluid out of ventricle50 produces a corresponding decrease in volume of ventricle 50 duringisovolumetric contraction.

Reference is now made to FIGS. 5 and 11. It is to be noted that passivepump 182 may be coupled to a port 64, as described hereinabove withreference to FIG. 5. Port 64 may be directly coupled to receptacle 184.Alternatively, receptacle 184 has a penetrable film and functions as aport.

Reference is now made to FIGS. 3A-G, 4A-B, and 10-11. It is to be notedthat passive pump 182 as described with reference to FIG. 11 operates inStages A-G as described in accordance with the operation of passive pump21 with reference to FIGS. 3A-G, the graph of FIG. 4A, the table of FIG.4B, and the pressure/volume graph of FIG. 10, mutatis mutandis.

Reference is now made to FIGS. 6A-B and 11. It is to be noted thatsystem 180 may comprise springs 86 coupled to receptacle 184 asdescribed hereinabove with reference to FIGS. 6A-B. Additionally, fluidis disposed within the internal space and is passable between receptacle184 and bag 186 via conduit 188. Typically, the internal space contains10-80 ml of fluid, e.g., 20-40 ml of fluid. Typically, the fluidcomprises fluid that is not blood of the patient. For some applicationsof the present invention, the fluid comprises a gas, such as carbondioxide, or a liquid, such as saline.

Reference is again made to FIG. 11. Passive pump 182 is implanted usinga transcatheter/transvascular approach and advantageously does notrequire making an incision in myocardial tissue of the heart of thepatient.

Reference is now made to FIGS. 12A-B, which are schematic illustrationsof a system 200 comprising a passive pump 202 comprising two bags 22 and204 and an energy-storage element 250 comprising a plurality of struts206, in accordance with some applications of the present invention. Bag204 typically functions as an extraventricular receptacle. It is to benoted that system 200 is similar to system 20 described hereinabove withreference to FIG. 1A, like reference numbers referring to like parts,with the exception that passive pump 202 does not comprise compliantballoon 24. Bags 22 and 204 have similar wall compliance (for example,effectively no compliance at pressures less than 120 mmHg). For someapplications, each of bags 22 and 204 has, in the absence of anyexternal forces applied thereto: (a) a first volume when bags 22 and 204each has an internal pressure of 120 mmHg, and (b) a second volume whenthe bags 22 and 204 each has an internal pressure of 10 mmHg, the firstvolume being less than 110% of the second volume.

Fluid is disposed within the internal space and is passable between bags22 and 204 via conduit 26. Typically, the internal space contains 10-80ml of fluid, e.g., 20-40 ml of fluid. Typically, the fluid comprisesfluid that is not blood of the patient. For some applications of thepresent invention, the fluid comprises a gas, such as carbon dioxide, ora liquid, such as saline.

It is to be noted that bag 204 has little to no wall compliance,however, the presence of stent structure 250 a imparts compliance to thesection of passive pump 202 that comprises bag 204 and energy-storageelement 250.

For some applications, similarly as shown in FIGS. 2, 3A-G, 5, 8, 9, and11, bag 204 may be positioned outside of the heart and function as anextracardiac receptacle. For some applications in which bag 204 is anextracardiac receptacle, conduit 26 passes through myocardium andfunctions as a transmyocardial conduit.

Energy-storage element 250 comprises a stent structure 250 a comprisinga plurality of struts 206 surrounding bag 204. Typically, struts 206comprise a flexible material, e.g., nitinol. A respective portion 230 ofeach of struts 206 is configured to (1) assume alongitudinally-elongated state upon the filling of the expandableextraventricular receptacle (e.g., bag 204) from the first state to thesecond, expanded state (FIG. 12A), (2) assume an energy-released,longitudinally-shortened state (FIG. 12B), and (3) return the expandableextraventricular receptacle (e.g., bag 204) from the second, expandedstate to the first state during a transition of energy-storage element250 (e.g., struts 206) from the longitudinally-elongated state towardthe longitudinally-shortened state. In the longitudinally-shortenedstate of portions 230 of struts 206 shown in FIG. 12B, portions 230 ofstruts 206 are each typically shaped so as to define a bend whichprojects laterally away from a central longitudinal axis ax1 of pump202. In such a manner, portions 230 expand radially and shortenlongitudinally with respect to axis ax1. It is to be noted that thefirst state and the second expanded state of bag 204 (i.e., theexpandable extraventricular receptacle) and the respective states ofintraventricular bag 22 shown in FIGS. 12A-B are not drawn to scale.

Each strut 206 extends longitudinally along an external surface of theextraventricular receptable (e.g., bag 204) in a direction (1) from aportion 240 of the extraventricular receptable (e.g., bag 204) that isfurthest from the intraventricular receptable (e.g., bag 22), and toward(2) the intraventricular receptable (e.g., bag 22). Pump 202 comprisesstent structure 30 which has a first portion that surrounds conduit 26.Energy-storage element 250 defines a second portion of stent structure30 that surrounds the extraventricular receptacle (e.g., bag 204). Apart of the first portion of stent structure 30 (i.e., a wider portion212) surrounds a portion of the intraventricular receptacle (e.g., bag22). Stent structure 30 is (i) compressed during delivery of pump 202into the body of the patient, and (ii) expandable during implantation ofpump 202 in the body of the patient. Once expanded, first portion 210 ofstent structure 30 is shaped so as to define (1) a narrowed portion 210at conduit 26 and (2) wider portion 212 than narrowed portion 210, atthe part of the first portion of the stent structure that surrounds theportion of the intraventricular receptacle (e.g., bag 22).

Stent structure 250 a has a longitudinally-shortened state (FIG. 12B)and an energy-storage state (FIG. 12A) upon bag 204 assuming a greatervolume. Once the pressure in the ventricle decreases during diastole,stent structure 250 a releases the energy stored in it, expelling thefluid from within bag 204 into bag 22. That is, stent structure 250 a isconfigured to (1) absorb energy upon filling of bag 204 (i.e., theextraventricular receptacle) from a first state to a second, expandedstate, and (2) release the energy to return bag 204 (i.e., theextraventricular receptacle) from the second, expanded state to thefirst state.

Reference is now made to FIGS. 3A-G, 4A-B, 10, and 12A-B. It is to benoted that passive pump 202 as described with reference to FIGS. 12A-Boperates in Stages A-G as described in accordance with the operation ofpassive pump 21 with reference to FIGS. 3A-G, the graph of FIG. 4A, thetable of FIG. 4B, and the pressure/volume graph of FIG. 10, mutatismutandis.

Reference is now made to FIGS. 13A-B, which are schematic illustrationsof a system 300 comprising a passive pump 302 comprising two bags 22 and304 and an energy-storage element 250 comprising a mesh 250 b, inaccordance with some applications of the present invention. Bag 304typically functions as an extraventricular receptacle. It is to be notedthat system 300 is similar to system 20 described hereinabove withreference to FIG. 1A, like reference numbers referring to like parts,with the exception that passive pump 302 does not comprise compliantballoon 24. Bags 22 and 304 have similar wall compliance (for example,effectively no compliance at pressures less than 120 mmHg). For someapplications, each of bags 22 and 304 has, in the absence of anyexternal forces applied thereto: (a) a first volume when bags 22 and 304each has an internal pressure of 120 mmHg, and (b) a second volume whenthe bags 22 and 304 each has an internal pressure of 10 mmHg, the firstvolume being less than 110% of the second volume.

Fluid is disposed within the internal space and is passable between bags22 and 304 via conduit 26. Typically, the internal space contains 10-80ml of fluid, e.g., 20-40 ml of fluid. Typically, the fluid comprisesfluid that is not blood of the patient. For some applications of thepresent invention, the fluid comprises a gas, such as carbon dioxide, ora liquid, such as saline.

It is to be noted that bag 304 has little to no wall compliance,however, the presence of mesh 250 b imparts compliance to the section ofpassive pump 302 that comprises bag 304 and energy-storage element 250.

For some applications, similarly as shown in FIGS. 2, 3A-G, 5, 8, 9, and11, bag 304 may be positioned outside of the heart and function as anextracardiac receptacle. For some applications in which bag 304 is anextracardiac receptacle, conduit 26 passes through myocardium andfunctions as a transmyocardial conduit.

Energy-storage element 250 comprises mesh 250 b surrounding bag 204 andconduit 26. Typically, mesh 250 b comprises nitinol or stainless steel.A first portion 308 of mesh 250 b is configured to (1) assume alongitudinally-elongated state upon the filling of the expandableextraventricular receptacle (e.g., bag 304) from the first state to thesecond, expanded state (FIG. 13A), (2) assume an energy-released,longitudinally-shortened state (FIG. 13B), and (3) return the expandableextraventricular receptacle (e.g., bag 304) from the second, expandedstate to the first state during a transition of energy-storage element250 (e.g., mesh 250 b) from the longitudinally-elongated state towardthe longitudinally-shortened state. As portion 308 of mesh 250 breleases the energy, portion 308 of mesh 250 b transitions toward anenergy-released state in which first portion 308 of mesh 250 b expandsradially and shortens longitudinally, with respect to a centrallongitudinal axis ax1 of the pump 302.

Mesh 250 b is (i) compressed during delivery of pump 302 into the bodyof the patient, and (ii) expandable during implantation of pump 302 inthe body of the patient. Once expanded from the delivery state, mesh 250b is shaped so as to define a second, narrowed portion 310 of mesh 250 bthat surrounds conduit 26, and a third, wider (typically flared) portion312 of mesh 250 b surrounds a portion of the intraventricular receptacle(i.e., bag 22). Wider portion 312 is typically wider than second,narrowed portion 310.

Mesh 250 b has a longitudinally-shortened state (FIG. 13B) and anenergy-storage state (FIG. 13A) upon bag 304 assuming a greater volume.Once the pressure in the ventricle decreases during diastole, portion308 of mesh 250 b releases the energy stored in it, expelling the fluidfrom within bag 304 into bag 22. That is, portion 308 of mesh 250 b isconfigured to (1) absorb energy upon filling of bag 304 (i.e., theextraventricular receptacle) from a first state to a second, expandedstate, and (2) release the energy to return bag 304 (i.e., theextraventricular receptacle) from the second, expanded state to thefirst state. It is to be noted that the first state and the secondexpanded state of bag 304 (i.e., the expandable extraventricularreceptacle) and the respective states of intraventricular bag 22 shownin FIGS. 13A-B are not drawn to scale.

It is to be noted that pump 302 is shown as having mesh 250 b surround aportion of bag 22, conduit 26, and bag 304. It is to be noted that pump302 may comprise mesh 250 b surrounding bag 304, while the portion ofbag 22 and conduit 26 may be surrounded by stent structure 30, asdescribed hereinabove with reference to FIGS. 1A-B, for example.

Reference is now made to FIGS. 3A-G, 4A-B, 10, and 13A-B. It is to benoted that passive pump 302 as described with reference to FIGS. 13A-Boperates in Stages A-G as described in accordance with the operation ofpassive pump 21 with reference to FIGS. 3A-G, the graph of FIG. 4A, thetable of FIG. 4B, and the pressure/volume graph of FIG. 10, mutatismutandis.

Reference is now made to FIGS. 14A-B, which are schematic illustrationsof a system 400 comprising a passive pump 402 comprising bag 22, anextraventricular receptacle 404 comprising a bellows 406, and anenergy-storage element 250 comprising a coil spring 250 c, in accordancewith some applications of the present invention. It is to be noted thatsystem 400 is similar to system 20 described hereinabove with referenceto FIG. 1A, like reference numbers referring to like parts, with theexception that passive pump 402 does not comprise compliant balloon 24.Bag 22 and bellows 406 has similar wall compliance (for example,effectively no compliance at pressures less than 120 mmHg). For someapplications, each of bag 22 and bellows 406 have, in the absence of anyexternal forces applied thereto: (a) a first volume when bag 22 andbellows 406 each has an internal pressure of 120 mmHg, and (b) a secondvolume when the bag 22 and bellows 406 each has an internal pressure of10 mmHg, the first volume being less than 110% of the second volume.

Bellows 406 is typically disposed between bag 22 (i.e., theintraventricular receptacle) and energy-storage element 250.

Fluid is disposed within the internal space and is passable between bag22 and bellows 406 via conduit 26. Typically, the internal spacecontains 10-80 ml of fluid, e.g., 20-40 ml of fluid. Typically, thefluid comprises fluid that is not blood of the patient. For someapplications of the present invention, the fluid comprises a gas, suchas carbon dioxide, or a liquid, such as saline.

It is to be noted that bellows 406 has little to no wall compliance,however, the presence of spring 250 c imparts compliance to the sectionof passive pump 402 that comprises bellows 406.

For some applications, similarly as shown in FIGS. 2, 3A-G, 5, 8, 9, and11, bellows 406 may be positioned outside of the heart and function asan extracardiac receptacle. For some applications in which bellows 406is an extracardiac receptacle, conduit 26 passes through myocardium andfunctions as a transmyocardial conduit.

Typically, energy-storage element 250 comprises coil spring 250 ccomprising a shape-memory material, e.g., nitinol. Energy-storageelement 250 comprises coil spring 250 c that is configured to (1) assumea compressed, longitudinally-shortened, state upon the filling of theexpandable extraventricular receptacle (e.g., bellows 406) from a firststate to a second, expanded state (FIG. 14A), and (2) return theexpandable extraventricular receptacle (e.g., bellows 406) from thesecond, expanded state to the first state (FIG. 14B) during a transitionof energy-storage element 250 (e.g., coil spring 250 c) from thecompressed, longitudinally-shortened state toward an energy-releasedstate of spring 250 c. As coil spring 250 c releases the energy, coilspring 250 c lengthens longitudinally, with respect to a centrallongitudinal axis ax1 of pump 402.

Bellows 406 and coil spring 250 c are surrounded by scaffolding 440,e.g., a frame or a housing. Energy-storage element 250 is coupled at afirst end 420 of energy-storage element 250 to an outer surface ofbellows 406, and at a second end 430 of energy-storage element 250 to aportion of scaffolding 440. During the absorbing and releasing of energyby energy-storage element 250, first end 420 of energy-storage element250 moves, respectively, toward and away from second end 430 ofenergy-storage element 250. For some applications, scaffolding 440 iscoupled to stent structure 30 that surrounds conduit 26 and a portion ofbag 22, as described hereinabove with reference to FIGS. 1A-B, forexample. For some applications, scaffolding 440 is part of stentstructure 30. Scaffolding 440 and stent structure 30 are (i) compressedduring delivery of pump 402 into the body of the patient, and (ii)expandable during implantation of pump 402 in the body of the patient.

Coil spring 250 c has an energy-storage state (FIG. 14A) upon bellows406 assuming a greater volume, and an energy-released state (FIG. 14B).Once the pressure in the ventricle decreases during diastole, coilspring 250 c releases the energy stored in it, expelling the fluid fromwithin bellows 406 into bag 22. That is, coil spring 250 c is configuredto (1) absorb energy upon filling of bellows 406 (i.e., theextraventricular receptacle) from a first state to a second, expandedstate, and (2) release the energy to return bellows 406 (i.e., theextraventricular receptacle) from the second, expanded state to thefirst state. It is to be noted that the first state and the secondexpanded state of bellows 406 (i.e., the expandable extraventricularreceptacle) and the respective states of intraventricular bag 22 shownin FIGS. 14A-B are not drawn to scale.

Reference is now made to FIGS. 3A-G, 4A-B, 10, and 14A-B. It is to benoted that passive pump 402 as described with reference to FIGS. 14A-Boperates in Stages A-G as described in accordance with the operation ofpassive pump 21 with reference to FIGS. 3A-G, the graph of FIG. 4A, thetable of FIG. 4B, and the pressure/volume graph of FIG. 10, mutatismutandis.

Reference is now made to FIGS. 15A-B, which are schematic illustrationsof a system 500 comprising a passive pump 502 comprising bag 22, anextraventricular receptacle 504 comprising a bellows 506, and anenergy-storage element 250 comprising a coil spring 250 d, in accordancewith some applications of the present invention. It is to be noted thatsystem 500 is similar to system 20 described hereinabove with referenceto FIG. 1A, like reference numbers referring to like parts, with theexception that passive pump 502 does not comprise compliant balloon 24.Bag 22 and bellows 506 have similar wall compliance (for example,effectively no compliance at pressures less than 120 mmHg). For someapplications, each of bag 22 and bellows 506 has, in the absence of anyexternal forces applied thereto: (a) a first volume when bag 22 andbellows 506 each has an internal pressure of 120 mmHg, and (b) a secondvolume when the bag 22 and bellows 506 each has an internal pressure of10 mmHg, the first volume being less than 110% of the second volume.

Typically, energy-storage element 250 comprises coil spring 250 dcomprising a shape-memory material, e.g., nitinol.

Coil spring 250 d surrounds bellows 506 at least in part. Coil spring250 d wraps around bellows 506 between folds 507 of bellows 506.

Fluid is disposed within the internal space and is passable between bag22 and bellows 506 via conduit 26. Typically, the internal spacecontains 10-80 ml of fluid, e.g., 20-40 ml of fluid. Typically, thefluid comprises fluid that is not blood of the patient. For someapplications of the present invention, the fluid comprises a gas, suchas carbon dioxide, or a liquid, such as saline.

It is to be noted that bellows 506 has little to no wall compliance,however, the presence of spring 250 d imparts compliance to the sectionof passive pump 502 that comprises bellows 506.

For some applications, similarly as shown in FIGS. 2, 3A-G, 5, 8, 9, and11, bellows 506 may be positioned outside of the heart and function asan extracardiac receptacle. For some applications in which bellows 506is an extracardiac receptacle, conduit 26 passes through myocardium andfunctions as a transmyocardial conduit.

Energy-storage element 250 comprises coil spring 250 d that comprises ashape-memory material that is configured to (1) assume alongitudinally-elongated state upon the filling of the expandableextraventricular receptacle (e.g., bellows 506) from a first state to asecond, expanded state (FIG. 15A), and (2) return the expandableextraventricular receptacle (e.g., bellows 506) from the second,expanded state to the first state (FIG. 15B) during a transition ofenergy-storage element 250 (e.g., coil spring 250 d) from thelongitudinally-elongated state toward an energy-released state of coilspring 250 d. As coil spring 250 d releases the energy, coil spring 250d transitions toward the energy-released state in which coil spring 250d shortens longitudinally, with respect to a central longitudinal axisax1 of pump 502.

Bellows 506 and coil spring 250 d are surrounded by scaffolding 540,e.g., a frame or a housing. For some applications, scaffolding 540 iscoupled to stent structure 30 that surrounds conduit 26 and a portion ofbag 22, as described hereinabove with reference to FIGS. 1A-B, forexample. For some applications, scaffolding 540 is part of stentstructure 30. Scaffolding 540 and stent structure 30 are (i) compressedduring delivery of pump 502 into the body of the patient, and (ii)expandable during implantation of pump 502 in the body of the patient.

Coil spring 250 d has an energy-storage state (FIG. 15A) upon bellows506 assuming a greater volume, and an energy-released state (FIG. 15B).Once the pressure in the ventricle decreases during diastole, coilspring 250 d releases the energy stored in it, expelling the fluid fromwithin bellows 506 into bag 22. That is, coil spring 250 d is configuredto (1) absorb energy upon filling of bellows 506 (i.e., theextraventricular receptacle) from a first state to a second, expandedstate, and (2) release the energy to return bellows 506 (i.e., theextraventricular receptacle) from the second, expanded state to thefirst state. It is to be noted that the first state and the secondexpanded state of bellows 506 (i.e., the expandable extraventricularreceptacle) and the respective states of intraventricular bag 22 shownin FIGS. 15A-B are not drawn to scale.

Reference is now made to FIGS. 3A-G, 4A-B, 10, and 15A-B. It is to benoted that passive pump 502 as described with reference to FIGS. 15A-Boperates in Stages A-G as described in accordance with the operation ofpassive pump 21 with reference to FIGS. 3A-G, the graph of FIG. 4A, thetable of FIG. 4B, and the pressure/volume graph of FIG. 10, mutatismutandis.

Reference is now made to FIGS. 1A-15B. It is to be noted that althoughsystems described herein are applied to assist and repair a failing leftventricle 50 of the heart of the patient, the systems described hereincan also be applied to assist and repair a failing right ventricle,mutatis mutandis. It is to be noted that bags 22, 84, 96, and 186;receptacles 94 and 184; balloon 24; and bellows 406 and 506 may comprisea polymer (e.g., polyurethane or any other suitable elastic material),which is configured to retain elasticity for an extended period of time.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

The invention claimed is:
 1. A method for repairing a heart, comprising:identifying a heart of a patient as having a reduced ejection fraction;and in response to the identifying, reducing wall stress of a ventricleof the heart by implanting apparatus that facilitates cyclical moving offluid that is not blood of the patient into and out of the ventricle ofthe heart, the moving comprising: during ventricular diastole, moving avolume of the fluid into the ventricle in a manner that produces acorresponding decrease in a total volume of blood that fills theventricle during diastole; and during ventricular systole, moving thevolume of the fluid out of the ventricle in a manner that produces acorresponding decrease in a total volume of the ventricle duringisovolumetric contraction of the ventricle.
 2. The method according toclaim 1, wherein implanting the apparatus comprises reducing a volume ofblood expelled by the ventricle during systole.
 3. The method accordingto claim 1, wherein moving the volume of the fluid out of the ventriclecomprises moving the volume of the fluid out of the heart.
 4. The methodaccording to claim 1, wherein implanting the apparatus comprisesimplanting apparatus including a bag, a compliant balloon and a conduitdisposed between and in fluid communication with the bag and thecompliant balloon, in a manner in which (1) the bag is disposed withinthe ventricle, and (2) the compliant balloon is disposed outside theventricle.
 5. The method according to claim 4, wherein wall complianceof the balloon is at least three times wall compliance of the bag. 6.The method according to claim 4, wherein the bag is noncompliant.
 7. Themethod according to claim 4, wherein implanting the apparatus comprisespositioning the bag in a left ventricle.
 8. The method according toclaim 4, wherein implanting the apparatus comprises positioning the bagin a right ventricle.
 9. The method according to claim 4, whereinimplanting the apparatus comprises: positioning the balloon at anextracardiac space, and positioning the conduit transmyocardially. 10.The method according to claim 4, wherein implanting the apparatuscomprises (1) positioning the balloon in a right atrium, and (2)positioning the bag in a left ventricle, and wherein the method furthercomprises implanting the apparatus in a manner in which the conduitextends from the left ventricle to the right atrium.
 11. The methodaccording to claim 1, wherein implanting apparatus comprises implantingapparatus including a first bag, a second bag and a conduit disposedbetween and in fluid communication with the first bag and the secondbag, in a manner in which (1) the first bag is disposed within theventricle, and (2) the second bag is disposed outside the ventricle. 12.The method according to claim 11, wherein the first and second bags arenoncompliant.
 13. The method according to claim 11, wherein implantingthe apparatus comprises positioning the first bag in a left ventricle.14. The method according to claim 11, wherein implanting the apparatuscomprises positioning the first bag in a right ventricle.
 15. The methodaccording to claim 11, wherein implanting the apparatus comprises:positioning the second bag at an extracardiac space, and positioning theconduit transmyocardially.
 16. The method according to claim 11, whereinimplanting the apparatus comprises positioning (1) the first bag in aleft ventricle, and (2) the second bag in a right atrium, and whereinthe method further comprises implanting the apparatus in a manner inwhich the conduit extends from the left ventricle to the right atrium.17. The method according to claim 11, wherein implanting the apparatuscomprises positioning (1) the first bag in a left ventricle, and (2) thesecond bag in a superior vena cava, and wherein the method furthercomprises implanting the apparatus in a manner in which the conduitextends from the left ventricle to the superior vena cava.
 18. Themethod according to claim 11, wherein implanting the apparatus comprisespositioning (1) the first bag in a left ventricle, and (2) the secondbag in an inferior vena cava, and wherein the method further comprisesimplanting the apparatus in a manner in which the conduit extends fromthe left ventricle to the inferior vena cava.
 19. The method accordingto claim 11, wherein the apparatus comprises an energy-storage elementcoupled to the second bag and configured to: absorb energy upon fillingof the second bag from a first state to a second, expanded state, andrelease the energy to return the second bag from the second, expandedstate to the first state.
 20. The method according to claim 19, whereinthe energy-storage element comprises a plurality of struts surroundingthe second bag, wherein a respective portion of each of the struts isconfigured to: assume a longitudinally-elongated state upon the fillingof the second bag from the first state to the second, expanded state,assume a longitudinally-shortened state, and return the second bag fromthe second, expanded state to the first state during a transition of theenergy-storage element from the longitudinally-elongated state towardthe longitudinally-shortened state.
 21. The method according to claim19, wherein the energy-storage element comprises a mesh having a firstportion surrounding the second bag, wherein the first portion of themesh is configured to: absorb the energy upon the filling of the secondbag from the first state to the second, expanded state, and release theenergy to return the second bag from the second, expanded state to thefirst state.
 22. The method according to claim 19, wherein the secondbag comprises a bellows, and wherein the energy-storage element iscoupled to the bellows.
 23. The method according to claim 1, whereinimplanting the apparatus comprises acutely further reducing the ejectionfraction and chronically increasing the ejection fraction.
 24. Themethod according to claim 4, wherein implanting the apparatus comprises(1) positioning the balloon in a superior vena cava, and (2) positioningthe bag in a left ventricle, and wherein the method further comprisesimplanting the apparatus in a manner in which the conduit extends fromthe left ventricle to the superior vena cava.
 25. The method accordingto claim 4, wherein implanting the apparatus comprises (1) positioningthe balloon in an inferior vena cava, and (2) positioning the bag in aleft ventricle, and wherein the method further comprises implanting theapparatus in a manner in which the conduit extends from the leftventricle to the inferior vena cava.